Define Imbibition. Describe Its Role In Ascent Of Sap And Seed Germination?


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When a substance absorbs water and swells up but does not dissolved in it, this process is called imbibition.
Role in ascent of sap and seed germination:
Imbibition is another force, which plays an important role in ascent of sap. Sacks in 1874 suggested that the water molecules move along the cell walls of xylem vessels due to to imbibition.

The cell wall components like cellulose, pectin and lignin take up water and as a result increase in volume, but the components do not dissolve in water, this phenomenon is called imbibition. A considerable imbibition force is developed in plant body. The root cell walls imbibe water from the soil, and this water moves by apoplast pathway.

Imbibition is a reversible process and when water is lost, the original volume of cell wall and of protoplasm is restored. The uptake of water by imbibition is especially important during germination of seeds. The volume of dry seed is increased up to 200 times by imbibition, as result the seed coat ruptures and makes the germination of seed effective.

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